rapid pinpointing of risk sites, while repetitive LIDAR can be used to assess storm
impacts on coastal geomorphology and sand storage (Stockdon et al., 2002).
Surges along the east coast of Canada can add up to 2 m or more of water to the
predicted water level along the coast (Parkes et al., 1997). A storm surge is defined by
the difference between observed water level and the level predicted for the astronomical
tide. Surges are caused by high winds and atmospheric low pressure systems associated
with storms. Coastal communities are most vulnerable if a storm surge makes landfall
during a high-tide event, especially during large spring high tides. With accelerated sealevel rise as described above, the extent and frequency of flooding will increase in the
future, as will the impact of related factors such as shoreline erosion. Thus, there will be
a growing demand for information products to predict areas at risk from such events, at
present and into the future, as a basis for sustainable coastal zone management,
effective planning, and the development of appropriate adaptation strategies. In this
chapter, following the introductory discussion of coastal flooding associated with sea
level rise and storm surges, we consider remote-sensing technologies available to
produce information products suitable for defining susceptible coastal areas. We then
describe a case study from Atlantic Canada, where a multi-disciplinary scientific team
has produced information products to aid local resource managers in identifying areas
prone to coastal flooding and erosion. The Planning Department for the City of
Charlottetown was involved in the project and has incorporated the flood risk and flood
depth maps into their GIS system to allow them to develop a policy to minimize
damage from future flooding events (Webster et al., 2003).
1.2 REMOTE SENSING TECHNOLOGIES FOR FLOOD RISK MAPPING
Remotely sensed data can be used in flood risk applications in two main ways: 1)
using remote sensing to map the extent of flooding (active, cloud-penetrating, sensors
such as synthetic aperture radar (SAR) on Radarsat are ideal for this application); and
2) using remote sensing to obtain high-resolution elevation information that can be used
in predicting flood-risk areas. Because storm surges are typically 0.6 to 2 m in height,
technologies with vertical precision significantly finer than these values must be
employed to generate flood risk maps of sufficient resolution. Airborne LIDAR (light
detection and ranging) is an emerging technology that offers the vertical accuracy and
high spatial sampling density required for this purpose. Many LIDAR systems have
vertical accuracies on the order of 15 cm or better. LIDAR technology has been
employed for a number of years in atmospheric studies (e.g. Post et al., 1996; Mayor
and Eloranta, 2001) and as an airborne technique for shallow bathymetric charting (e.g.
Guenther et al., 2000), although cost remains an impediment to widespread acceptance
for the latter purpose. The technology can also be used to image the land and water
surface (Hwang et al., 2000), as in the case study presented here. A general overview of
airborne laser scanning technology and principles is provided by Wehr and Lohr
(1999). Applications have been demonstrated in forestry (Maclean and Krabill, 1986),
sea-ice studies (Wadhams et al., 1992), and glacier mass balance investigations (Krabill
et al., 1995, 2000; Abdalati and Krabill, 1999). Use of LIDAR in coastal process
studies in the USA have been reported by Sallenger et al. (1999), Krabill et al. (1999),
and Stockdon et al. (2002), among others. Preliminary trials in Atlantic Canada were
reported by O’Reilly (2000) and subsequent efforts described by Webster et al. (2002).
Most of the coast of the conterminous USA has now been mapped using this
technology (Brock et al., 2002).
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impacts on coastal geomorphology and sand storage (Stockdon et al., 2002).
Surges along the east coast of Canada can add up to 2 m or more of water to the
predicted water level along the coast (Parkes et al., 1997). A storm surge is defined by
the difference between observed water level and the level predicted for the astronomical
tide. Surges are caused by high winds and atmospheric low pressure systems associated
with storms. Coastal communities are most vulnerable if a storm surge makes landfall
during a high-tide event, especially during large spring high tides. With accelerated sealevel rise as described above, the extent and frequency of flooding will increase in the
future, as will the impact of related factors such as shoreline erosion. Thus, there will be
a growing demand for information products to predict areas at risk from such events, at
present and into the future, as a basis for sustainable coastal zone management,
effective planning, and the development of appropriate adaptation strategies. In this
chapter, following the introductory discussion of coastal flooding associated with sea
level rise and storm surges, we consider remote-sensing technologies available to
produce information products suitable for defining susceptible coastal areas. We then
describe a case study from Atlantic Canada, where a multi-disciplinary scientific team
has produced information products to aid local resource managers in identifying areas
prone to coastal flooding and erosion. The Planning Department for the City of
Charlottetown was involved in the project and has incorporated the flood risk and flood
depth maps into their GIS system to allow them to develop a policy to minimize
damage from future flooding events (Webster et al., 2003).
1.2 REMOTE SENSING TECHNOLOGIES FOR FLOOD RISK MAPPING
Remotely sensed data can be used in flood risk applications in two main ways: 1)
using remote sensing to map the extent of flooding (active, cloud-penetrating, sensors
such as synthetic aperture radar (SAR) on Radarsat are ideal for this application); and
2) using remote sensing to obtain high-resolution elevation information that can be used
in predicting flood-risk areas. Because storm surges are typically 0.6 to 2 m in height,
technologies with vertical precision significantly finer than these values must be
employed to generate flood risk maps of sufficient resolution. Airborne LIDAR (light
detection and ranging) is an emerging technology that offers the vertical accuracy and
high spatial sampling density required for this purpose. Many LIDAR systems have
vertical accuracies on the order of 15 cm or better. LIDAR technology has been
employed for a number of years in atmospheric studies (e.g. Post et al., 1996; Mayor
and Eloranta, 2001) and as an airborne technique for shallow bathymetric charting (e.g.
Guenther et al., 2000), although cost remains an impediment to widespread acceptance
for the latter purpose. The technology can also be used to image the land and water
surface (Hwang et al., 2000), as in the case study presented here. A general overview of
airborne laser scanning technology and principles is provided by Wehr and Lohr
(1999). Applications have been demonstrated in forestry (Maclean and Krabill, 1986),
sea-ice studies (Wadhams et al., 1992), and glacier mass balance investigations (Krabill
et al., 1995, 2000; Abdalati and Krabill, 1999). Use of LIDAR in coastal process
studies in the USA have been reported by Sallenger et al. (1999), Krabill et al. (1999),
and Stockdon et al. (2002), among others. Preliminary trials in Atlantic Canada were
reported by O’Reilly (2000) and subsequent efforts described by Webster et al. (2002).
Most of the coast of the conterminous USA has now been mapped using this
technology (Brock et al., 2002).
158
Webster and Forbes